The present invention generally pertains to current sources for electronic circuits and is particularly directed to a system for establishing a precise reference current and steering the current through a load.
In some electronic circuit applications it is necessary to establish a precise reference current during one interval and then provide the precise reference current to a load during a subsequent interval. For example in an analog-to-digital converter described in a co-pending patent application, Ser. No. 910,506, entitled "Expanded Analog-to-Digital Converter Having One-Half LSB Shift", filed on even date herewith by the inventor herein and Ronald Winston Russell, there is a requirement for a precise reference current source which provides a reference current to a resistance ladder during prescribed intervals. In such an analog-to-digital converter it is preferred to continuously reestablish the precise reference current when such current is not required in the operation of the converter.